Describe the objective of particle size analysis in pharmaceuticals and list the limitations of the sieving method.

The objective of particle size analysis in pharmaceuticals is to characterize the size distribution of particles, which directly impacts critical product attributes such as dissolution rate, bioavailability, content uniformity, flow properties, and stability. This analysis is essential for quality control, process optimization, and predicting the performance of drug formulations.

Limitations of the sieving method for particle size analysis include:

• Limited range: Not suitable for very fine particles (typically below 45-50 $\mu$m) due to aggregation and difficulty in passing through small apertures.
• Particle shape dependency: Sieving separates particles based on their smallest dimension, which may not represent the true particle size for irregularly shaped particles.
• Attrition and agglomeration: Particles can undergo attrition (breakage) during prolonged sieving, or agglomerate (clump together), leading to inaccurate results.
• Time-consuming: The process can be lengthy, especially for fine powders requiring extended sieving times to ensure complete separation.